The present invention relates to a split crankcase radial compressor, such as a scotch yoke radial compressor adapted for use in an automotive air-conditioner. Specifically, the invention is related to the external housing assembly and the means for connecting the housing halves together as well as the means for connecting the two halves of the crankcase together.
Automotive air conditioning systems require small, lightweight compressors which can be conveniently mounted to the engine and driven by the same belt system that drives the fan, alternator and power steering pump. One compressor which has been found to meet these requirements is a radial compressor wherein a plurality of pistons are reciprocated within cylinders radially disposed about the crankshaft.
One problem with this type of compressor, however, is the difficulty of assembling the pistons to the crankshaft and crankcase. One prior art approach is to insert the pistons through the cylinders and then press fit them to the yoke assembly. A more satisfactory technique is disclosed in U.S. Pat. No. 3,910,164, which discloses a radial compressor wherein the crankcase is split, with each of the two halves including a plurality of semicylindrical cross recesses. The piston assembly is placed in one of the crankcase halves and then the other half is secured thereto. An improvement to this basic type of compressor is disclosed in copending U.S. patent application Ser. No. 939,877 filed Sept. 5, 1978, now U.S. Pat. No. 4,273,519 which is owned by the assignee herein. The compressor which is the subject of that patent application solves the problem of providing a good seal between the crankcase halves by preassembling the pistons with stamped steel cylinder liners prior to assembly with the crankcase. The liners prevent cylinder leakage through the interface between the crankcase halves and provide the desired compatability for wear against the aluminum pistons.
In the compressor disclosed in the aforementioned application Ser. No. 939,877, an external housing, which is also of a two-piece construction, encloses the crankcase and forms the intake and outlet chambers. A significant problem in the construction of a lightweight automotive compressor incorporating such a housing as the high pressure envelope, is that of obtaining sufficient strength in the housing to withstand safety required burst pressure levels. To rely only on the weld around the interface of the housing halves is often not satisfactory to meet safety standards. In order to solve this problem, the present invention strengthens the flexible ends of this type of housing by incorporating tie rods which are rigidly connected to the housing halves as by welding, riveting, etc.
From the standpoint of good strength and to minimize the overall size of the compressor, it is advantageous to pass the tie rods through openings in the crankcase halves. This creates a secondary problem, however, which is the creation of a possible internal leak path from the high pressure cavity to the low pressure cavity in the area of the openings formed to accommodate the passage of the tie rods.